Breast cancer diagnosisis one of the most difficult events that a woman canexperienceduring her life and it usually produceshigh levels of stress. Globalmeasuresof perceivedstress are useful for screeningand for comparingstresslevels between cancer patients and other clinical and nonclinicalpopulations.Onesuch instrumentthat is widely used is the PerceivedStress Scale (pss‐10), but itspsychometricpropertieshave scarcely been analysed with breast cancer patients.Theaimofthisstudywastoprovidevalidityevidenceregardingtheuseofthe10‐itemversionofthepss‐10 asatoolformeasuringperceivedstressinthiscontext.Participantswere 215 Spanish breast cancer patients who completedthe PSS‐10andthe DASS‐21,a measureofaffective distress(depression,anxiety,andstress).The internal structureof the PSS‐10 was examinedthrough confirmatoryfactoranalysis (CFA), and the reliabilityof test scores was estimatedusing McDonald'somegacoefficient.Validityevidencebasedonrelationshipswithothervariableswasalsoobtainedusingcorrelationanalysis.TheCFAsupportedacorrelatedtwo‐factorstructure:perceivedhelplessness(sixnegativelywordeditems)andperceivedself‐efficacy (four positivelyworded items). Reliabilitycoefficientsfor scores on thesetwofactorswere0.87and0.73,respectively.Scoresonaffectivedistress(DASS‐21)werestronglyandpositivelycorrelatedwithperceivedhelplessnessandmoderatelyand negativelycorrelatedwith perceivedself‐efficacy.The PSS‐10 is an adequatetool for measuringperceivedstress in the breast cancer context and it may beusefulfor identifyingwomenat riskofpsychologicalmaladjustment.