Purpose This study aims to explore the psychological effects of lockdown during the early stages of the COVID-19 pandemic on people living in an Italian prison. The suspension of family visits and most activities, along with the difficulties in applying social distancing to this vulnerable population was associated with increased psychological distress. Riots broke out over two days in more than 22 prisons across Italy at the beginning of March 2020, highlighting the negative psychological impact of the pandemic and the country’s emergency policies. Design/methodology/approach The research involves 17 men (Italians and foreigners) detained in a Lombardy prison from 1 March to 4 May 2020, corresponding to the lockdown phase in Italy. The qualitative content analysis (CA) of 27 posts, written by participants during that period and published on the blog “L’Oblò”, were analysed. The analysis allowed the identification of topics and subtopics that are related to two major categories of content: cognitions and emotional connotations about the COVID-19 lockdown in prison. Findings Analysis showed that blog post content was predominately negative in terms of emotional connotations. The most frequent coded negative emotional connotations were: missing, worry, psychological pain and fear, whilst the most frequent coded positive emotional connotations were: hope and gratitude for the support they received from prison workers. The rest of the blog content was coded as “cognitions”. Cognitions were coded as descriptions of lockdown effect on detention; prison during the COVID-19 emergency; the pandemic situation in general; and comparison between inside and outside prison. Originality/value The current study is original as it describes through blog CA the psychological condition of prisoners during the first COVID-19 pandemic lockdown in the most affected region in Italy.