Perfectionism and Perseverative negative thinking/PNT are both associatedwith OC symptoms. PNT is a prime candidate when investigating the pathway thatlinks perfectionism to psychopathology.

To investigate if PNT mediates the relationshipbetween perfectionismcognitions and OC symptoms.

464 (72.5%females) students (mean age 22.5±4.5 years) participated in an online surveyincluding the Portuguese validated versions of Maudsley O-C Inventory/MOCI (toassess Doubting and Rumination/DR, Checking and Cleaning), PerseverativeThinking Questionnaire/PTQ-15 (Repetitive Thought/RT, Cognitive interferenceand unproductiveness/CIU), Multidimensional Perfectionism CognitionsInventory/MPCI (Concern over Mistakes/CM, Personal Standards/PS, Pursuit of Perfection/PP). Negative affect/NA was assessed with the Profile of Mood States.

Significantpredictors of MOCI_Total were PP (b=.131),RT (b=.228)and CIU (b=.254)(all p<.01). RT (95%CIBCa=.761-1.482) and CIU (95%CI=.813-1.551) were partial mediators of therelationship between MOCI_Total and PP.

DR waspredicted by CM (b=.107),PP (b=.107),RT (b=.333)and CIU (b=.281)(all p<.01). Both RT and CIU were partial mediators of the relationship betweenperfectionism and DR (all the 95%CI not contained zero).

Checkingwas predicted by PP (b=.120), RT (b=.154) andCIU (b=.267)(all p<.01). RT (95%CI =.027-.056) and CIU (95%CI=.086-.128) were partialmediators of the relationship between Checking and PP.

Cleaning wasonly predicted by PP (b=.174; p=.001).

QPP-15_Totaland IMCP_Total were mediators of the association of MOCI_Total (and itsdimensions DR and Checking) with NA.