A study has found that only half of people are able to identify the correct position of the heart, and many more are flummoxed by other human anatomy.
According to researchers from King's College London, just a third of the 722 people questioned at Kings, Guy's and St Thomas's hospitals were able to say where in the body the lungs were.
The findings published in the medical journal BMC Family Practice show that on average each participant only got half of the answers right.
The results were no better than a similar survey carried out in 1970, even though people have better access to information.
Even if people had a medical problem with the organ they were trying to identify, they struggled to locate its position in their body.
As part of the study participants were shown drawings of a male or female body with organs shown in different positions, one of which was correct.
Researchers said: "Healthcare professionals still need to take care in providing organ specific information to patients and should not assume that patients have this information, even for those organs in which their medical problem is located.
"The consultation may offer many opportunities for both checking and improving patients' knowledge."