Introduction Along last years psychiatric literature has shown an increased interest about Borderline Personality Disorder (BPD) diagnosis. Nevertheless, few studies in large samples has been developed in our country. This study is a part of a main research: Personality Disorders in Andalusian Community. Diagnostic evolution and its link with use of health services. Objectives • To study BPD diagnosis in Andalusian inpatients throughout the last 10 years. • To establish a predictive model analyzing the BPD diagnostic evolution. Method The information has been obtained from the Basic Information Minimum Set: A record of admissions (with clinical and demographic variables) registered in the Andalusian population. We made an observational naturalistic study about the number of inpatients with BPD diagnosis, and an analytical study (Linear Regression) to determine the trend marked in the last years about evolution in the diagnosis of inpatients with Personality Disorders (PD). Results The number of total psychiatric admissions was 99444 (64968 inpatients): 10755 records had a Personality Disorder (PD) diagnosis.The number of patients with BPD diagnosis has increased from 75 in 1995 to 340 in 2004 (11,8% to 26,13% over percentage of PD). The linear regression had a thread of 0,95, with a determination coefficient of 91,6% (standard error 0,34), with statistical significance (p = 0,00), establishing a prediction linear model about the increase of inpatients with BPD diagnosis. Conclusions 1. The number of inpatients with BPD diagnosis in Andalusia is increasing over last years. 2. The model predicts a growing of BPD diagnosis along next years.