Background: Lot of research has focused on working memory (WM) deficits as trait markers and endo phenotypes in schizophrenia. Acute and transient psychotic disorders (ATPD) have on the other hand been traditionally viewed as completely remitting good prognosis psychosis and very little research has focused on whether cognitive deficits similar to schizophrenia are present in such patients. No study is available on WM in such patients in remission or on their relatives. Aims and objectives: The current study aims at mapping working memory deficits in patients of acute and transient psychotic disorders in clinical remission and their non affected first degree relatives. This will help to determine if cognitive deficits exist in ATPD and if they are underlying genetic markers and endo phenotypes for ATPD Methods: The study is of prospective cross sectional design carried out on a sample of 17 of which 6 were patients and 11 were first degree relatives. The measures of Working memory were Visual and Verbal N back memory, and Rey's Complex Figure Test with exposure & copy and immediate & delayed recall Statistical Analysis: Kruskall-Wallis test was used to find the difference between performance of the patients and relatives with the normative data. Significant difference was found between the sample performance and the normative data on Visual 1 back hit (0.04) and error (0.01), Verbal 1 back hit (0.02) and error (0.00) and Rey- Osterrith Figure exposure and copy (0.00). However, no difference was found between the performance of patients and their relatives Results: Patients of ATPD show significant deficits in working memory even when symptoms have completely remitted as do their asymptomatic first degree relatives. Conclusions: Working memory deficits may be considered to be endo phenotypes in ATPD.