Introduction Symptomatic central nervous system (CNS) toxoplas- mosis rarely develops during primary infection in normal hosts [1]. Several reports of acute toxoplas- mosis in normal hosts have appeared since 1975 [2, 3, 4]. The acquired CNS infection can present as meningoencephalitis during primary infection in an immunocompetent host or as an intracerebral mass lesions or encephalitis in immunocompromised hosts [1]. CNS toxoplasmosis has increased dramatically and is one of the most common and most important opportunistic infections in patients with the acquired immune deficiency syndrome (AIDS). It has a preva- lence of 3–40%, depending on the seroprevalence [5]. More than 95% of toxoplasma encephalitis in patients with AIDS is due to reactivation of a chronic latent infection [6]. Imaging in toxoplasma encephalitis in the immuno- compromised is well documented [7, 8, 9]. We present MRI features in two immunocompetent patients pre- senting with toxoplasma encephalitis. To the best of our knowledge, this is the first report in the English-language literature describing the MRI features of diffuse tox- oplasma encephalitis in immunocompetent patients. Case reports Case 1 A 22-year-old man, previously in good health, presented with fever, headache and mild weakness on the left, followed by gradual loss of Neuroradiology (2002) 44: 834–838 DOI 10.1007/s00234-002-0852-5 DIAGNOSTIC NEURORADIOLOGY P.B. Vastava S. Pradhan S. Jha K.N. Prasad S. Kumar R.K. Gupta MRI features of toxoplasma encephalitis in the immunocompetent host: a report of two cases Received: 10 December 2001 Accepted: 6 July 2002 Published online: 24 August 2002 Ó Springer-Verlag 2002 P.B. Vastava Æ S. Kumar Æ R.K. Gupta (&) Department of Radiology, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Rae Bareli Road, Lucknow 226014, UP, India E-mail: rgupta@sgpgi.ac.in Tel.: +91-522-440900 Fax: +91-522-440017 S. Pradhan Æ S. Jha Department of Neurology, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Rae Bareli Road, Lucknow 226014, UP, India K.N. Prasad Department of Microbiology, Sanjay Gandhi Post-Graduate Institute of Medical Sciences, Rae Bareli Road, Lucknow 226014, UP, India Abstract Central nervous system involvement due to toxoplasmosis in an immunocompetent host is rare. We describe MRI features in two immunocompetent patients with of cerebral toxoplasmosis and compare these with those for the immuno- compromised host. Keywords Toxoplasmosis Æ Brain Æ Magnetic resonance imaging