This study was conducted to assess the nutritional status of prisoners living with HIV/ AIDS in Tanzania prisons. A total of 768 (384 HIV-infected, 384 non-infected) prisoners were assessed for nutritional status, dietary intake, Hb status and body fat mass. Results showed that, 75.5% (N=768) of prisoners had good nutritional status of whom 38.3% were HIV-infected and 37.2% were non-infected inmates. About 6.6% (N=768) of the inmates were under-weight, (2.9% HIV-infected, 3.7% non-HIV infected). The study also revealed that, 62.7% (N=768) of the prisoners were anaemic (32.2% being HIV-infected and 30.5% non-HIV infected). Dietary intake revealed that, average energy consumption was above the WHO (2002) recommended dietary intake (2100-2510 kcal for HIV-infected and 2100 kcal for non-HIVinfected) while protein intake was lower than the WHO recommended dietary intake (50-80g). Body fat mass composition showed that, 57.3% (N=768) of the respondents were healthy (31.0% HIV-infected, 26.3% non-infected) while 30.9% (N=768) were either over-fat or obese (13.5% HIV-infected, 17.4% non-infected). The nutritional status of majority of the prisoners was generally good, although there were small proportions of inmates who were overweight (13.9%, N=768), obese (4%, N=768) and under-weight (6.6%, N=768).Haemoglobin status showed that, 11.3% (N=768) of the inmates were moderately anaemic, 51.4% were mildly anaemic while only 37.3% had normal Hb levels. It was concluded from this study that, poor nutritional status is still a problem among prisoners as some were under-weight while others were over-weight and obese. Iron deficiency anaemia was also a serious problem among many prisoners. It is therefore recommended that, nutritional status monitoring should be conducted among prisoners and appropriate interventions should be made to improve their nutritional status especially of those who are under-weight, over-weight, obese and anaemic.