The Physician Global Assessment International Standardisation COnsensus in Systemic Lupus Erythematosus (PISCOS) study aimed to obtain an evidence-based and expert-based consensus standardisation of the Physician Global Assessment (PGA) scoring of disease activity in systemic lupus erythematosus (SLE). An international panel of 79 SLE experts participated in a three-round Delphi consensus process, in which 41 statements related to the PGA in SLE were rated, using a 0 (strongly disagree) to 10 (strongly agree) numerical rating scale. Statements with agreement of 75% or greater were selected and further validated by the expert panel. Consensus was reached on 27 statements, grouped in 14 recommendations, for the use of the PGA in SLE, design of the PGA scale, practical considerations for PGA scoring, and the relationship between PGA values and levels of disease activity. Among these recommendations, the expert panel agreed that the PGA should consist of a 0–3 visual analogue scale for measuring disease activity in patients with SLE in the preceding month. The PGA is intended to rate the overall disease activity, taking into account the severity of active manifestations and clinical laboratory results, but excluding organ damage, serology, and subjective findings unrelated to disease activity. The PGA scale ranges from “no disease activity” (0) to the “most severe disease activity” (3) and incorporates the values 1 and 2 as inner markers to categorise disease activity as mild (≥0·5 to 1), moderate (>1 and ≤2) and severe (>2 to 3). Only experienced physicians can rate the PGA, and it should be preferably scored by the same rater at each visit. The PISCOS results will allow for increased homogeneity and reliability of PGA ratings in routine clinical practice, definitions of remission and low disease activity, and future SLE trials.